Policy Routing Based on Traffic Source
Consider the example shown in Figure 8-6. Assume that AS1 was assigned network numbers from two different providers. The 10.10.10.0/24 range was taken from AS3, and the 11.11.11.0/24 range was taken from AS4. AS1 wants to have any traffic originated from its 10.10.10.0/24 networks to be directed toward AS3 and traffic from its 11.11.11.0/24 networks to be directed to AS4, irrespective of the traffic's final destination. AS1 could use policy routing to achieve this requirement..
Purposefully Resetting BGP Peer Connections
Example 12-3 shows how to reset neighbor connections by using the neighbor shutdown command and, along the way, shows the various BGP neighbor states. The example uses routers R1 and R6 from Figure 12-2, as configured in Example 12-2. Example 12-3 Examples of Neighbor States All BGP neighbors can be reset with the clear ip bgp * exec command, which, like the neighbor shutdown command, resets the neighbor connection, closes the TCP connection to that neighbor, ..
Contents of the Neighbor Table
The neighbor table includes the following information: • The Layer 3 address of the neighbor. • The interface through which the neighbor's Hello was heard. The holdtime, or how long the neighbor table waits without hearing a Hello from a neighbor, before declaring the neighbor unavailable and purging the database. Holdtime is three times the value of the Hello timer by default. • The uptime, or period since the router first heard from the ne..
Multicast Addressing for Updates
EIGRP uses both multicast and unicast addressing. Some packets are sent reliably using Real-Time Protocol (RTP), a Cisco proprietary protocol that oversees the communication of EIGRP packets. These packets are sent with sequence numbers to make the transmission of data reliable. Hellos and ACKs do not require acknowledgement. Incremental updates cannot be anticipated; therefore, update, query, and reply packets must be acknowledged by the receiving neighbor.&nbs..
Multiplexing is a fundamental element of network design. Indeed, you could argue that a network is typically one huge multiplexing system. More specifically, however, multiplexing is a tool that provides economies of scale—multiple users share one large resource rather than a number of individual resources. NOTE Multiplexing is the aggregation of multiple independent traffic flows into one large traffic flow. A useful analogy is the freeway system, which mul..
